This interactive flash animation allows students to compare the sizes of the smallest organisms we know of on our planet. Starting with the head of a pin at 2 millimeters in diameter, students can use this animation to compare the relative sizes of cells and organisms small enough to sit on a pinhead. Nearly invisible without magnification, dust mites dwarf pollen grains and human cells. In turn, bacteria and viruses are even smaller. [Source: CELLS alive! J. Sullivan, Website: http://www.cellsalive.com] Grade level: 4-College.

This material is based upon work supported by the National Science Foundation (NSF) under Grant # NSF OCE-0707385. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF.